Mariner s compass



(No Model.)

R. OLIVER. MARINBRS COMPASS.

fweizaz 15036 Wfeawye," Mm

` UNITED STAT-Es PATENT OFFicn.

ROBERT OLIVER, OF BROOKLYN, NEW YORK.

MARINYERSiCOM PASS.

SPECIFICATION forming part of Letters Patent No. 478,017, dated June 28,1892.

Application filed March 7, 1892. Serial No. 424.047. (No model.)

To all whom it may concern/5 Be it known that I, ROBERT OLIVER, asubject ot the Queen of Great Britain, but having declared my intentionof becoming a citizenof the United States, residing atBrooklyn, in thecounty of Kings and Stateof New York, have invented new and useful'lmprovements in Mariners Compasses, of which the following is aspecification. Y

My invention relates to mariners compasses, the purpose thereof being toprovide a liquid compass in which the polar force is distributed overthe face of the card by independent parallel magnet-ized needles securedto the card in a novel manner and having their terminals in theperipheral line, whereby the polar attraction is more nearly equalizedupon all sides of the pivotal support.

It is my further object to provide a compass having a bowl formed in onepieceY of metal and provided with an expansion-chamber beneath the bowl.

It is my further purpose to provide a mariners compass having thecompass-card provided with a plurality of needles having novel mountingand providedY with an attachable and detachable ring air-chamber, incombination with a bowl having an eXpansion-chamber beneath, the cardbeing centered by a suitable bearing and sustained by an oil of asuitable color, whereby the rusting of the needles is prevented.

It is an important feature of my invention that I seek to obtain such a'distribution of magnetic force or polar attraction that instead ofbeing centered at two points or foci, as in thetwo-needle compass, itshall be scattered over all the many points in which polar attractionmay locate, being apportioned in substantial uniformity to each point,by which construction the compass shows less error.

It is my object, also, to add to the sensitiveness of the compass-cardby extending the multiple points of location of polar attraction inparallelism upon each side ofthe polaraxis fully as far as the edge ofthe card and arranging the same directly upon the compasscard, orsubstantially so, Wherebyl largely increase the directive force, or, inother words, obtain a compass which is more constantly upon the magneticmeridian. I also alm to avoid the presence ofv a species of magneticfulcrum, which is often found in other compasses, whereby the magneticpull or push will create larger errors than are possible with a compassmanufactured in accordance with my invention.

' My invention also comprises certain novel features of construction andnew combinations of parts, all ofl which will be fully set forthhereinafter, and then specifically pointed out in the claims followingthis specification. a

To enable others skilled in the art to make, construct,and use my saidinvention,-I will describe the same in detail, reference being had tothe accompanying drawings, inwhich- Figure l is a plan view of acompass, showing my invention. Fig. 2 is a central vertical section ofthe same.V Fig. 3 is a bottom plan view of the compass-card removed fromthe bowl.

In the said drawings the reference-numeral l indicates the compass-bowl,which is circular in plan View and having in its upper and largerportion la bowl 2 of suitable depth to contain a body of oil to giveflotation to the card in such degree as to require from the centralpivotal bearing merely the function of centering the card in the bowl,the weight sustained being onlysuiiicient to insure maintenance ofpivotal engagement between a central needle-pivot 3 in the bowl, whichenters a central cap 4 on the card and rests in an agate bearing 5,which is detachable.

The body of the compass below the bowl is contracted in radialdimensions to provide a chamber 6 beneath the bowl, but having its.

circular wall integral with the other parts described. Theexpansion-chamber is separated from the bowl `by a septum or diaphragm7, which forms the bottom of the bowl, and is provided with a series ofopenings 8, suitably arrangedin its central portion. One of theseopenings is in the bowl-center to receive the pivot-bearing 3. The bowlis formed of brass or other suitable metal or material, and the lowerpart of the body is formedin a separate part 9, attachable by screws,inclosing the bottom of the expansion-chamber 6 and forming aballast-weighty for the compass-body. The latter is supported in a ring10, which is provided with the usual gimbal-supports 12. Thecompass-bowl 2 is closed above by a IOO strong glass plate 13, laid uponthe circumferential edge 14, in which a surrounding channel 15 isprovided next the edge of the glass. In this channela rubber or othergasket16 is laid. Upon this is placed the gasketannulus 17, and screws18 are passed through openings in the annulus and into threaded openingsin the circumferential edge 14, thereby compressing the gasket in thechannel 15 and making an air-tight joint.

The compass-card is composed of a flat annulus 1 9 of suitablematerial-such as linen-having a hard-paint surface. Its width issufficient to allow the points and properindications or markings to beplaced thereon. Crossing the open interior space of the annulus on eachside of the centerisa bridge-piece 20, formed of brass or other suitablemetal in very thin strips, bent longitudinally to form two strips, onelying at right angles with the other. One of these strips is laid flatagainst the under face of the card, to which its end portions areattached by screws or in any other suitable manner. The bridge-piecesbeing parallel, they will have their angular strips projecting at rightangles to the face of the card, and through these angular strips holesare drilled at suitable intervals to receive the magnetized needles 21,which may be fastened by a small drop of soft solder or by any preferredmeans. The ends of these needles extend to the outer periphery of thecard, and the series of said needles extend over the whole card-spacefrom east to west, separated by uniform intervals. The extremes 22 ofthe series lying at the east and west extremes of the equatorial lineare short, but equal to each other, and upon each side of the linejoining the polar extremes I provide a field of polar attraction, whichis substantially equal in force and extent to the similar field upon theotherside of said line,the diminished length of the extremes 22 beingpartly compensated by the greater radial distance from the center.

Over the needles is arranged an air-chamber 23 of annular form andattached to the bridge-pieces by screws. air-chamber is of suitabledimensions to contain a body of air sufficient to nearly float thecompass-card and raised above the same far enough to locate the centerof gravity below the point of pivotal support. The latterconsists of acentral cap 4, havin g an agate bearing 5, which receives the centralpoint rising from the bowl. The cap 4 is connected to two of theneedles, one on each side of the polar diameter, the fastening being bymeans of attachable and detachable clasps 24.

Theconstruction setforth affords great delicacy of oscillation upon thepivotal center and insures a corresponding high degree of accuracy. Theoil reduces the vibrations of the needles and practicallyeliminates itsaxial movement while the nature of said liquid prevents the accumulationof rust on the needles, and also is free from excessive ex- ',thecentral support. construction.

pansion and contraction by change of temperature.

The lower portion of the expansion-chamber 6 is closed by a diaphragm6a, which preferably is slightly convex on its upper face, as shown inFig. 2, and its marginal portion is bent to form an outer rim or flange24, which lies closely against the inner circular face of the flange,which depends from the bottom of the compass-bowl. Between the flange 24and the bottom 6 of the expansion-chamber a circumferential elastic rim25 is formed by carrying the metal alittle above the floor 6a and thenbending it upon itself to form the outer rim or flange 24a.

The convexity of the floor and the elastic yield of these parts is suchas to enable the chamber 6 to adapt its capacity to all the changesproducedby changes of temperature, &c. As the body of oil expands with arise of temperature, the floor 6a of the expansionchvamber yieldsslightly, and is put under such a degree of elastic tension that ascontracphragm 7, having openings 8 for communication, I am able toremove a large part of the whole volume of oil from the compass-bowlywithout detracting in any respect from the ,results sought and withmaterial benefit in obtaining a perfect light upon the compasscard,since the bowl being so much shallower the reflection of light from thebottom i is much greater. The disturbance of the oil in the bowl, due tothe oscillation of the vessel, is less with a small than with a largebody ot' oil, and the creation of counter-currents is i practicallyavoided. This ring-shaped In securing the cap 4 to the card I usuallyinsert screws through openings in the flange l of the cap, said screwsbeing tapped into the clamps 24, resting on the needles adjacent to Thisis the preferred It is essential in this class of Compasses l that theelastic yield of the bottom of the expansion-chamber be sufficient tocompensate for the expansion and contraction of the fluid in thecompass-bowl under extremes of temperature ranging from freezing up tothe heat of a tropical sun.

If the yield is not ample in degree, the pressure will be exerted uponthe glass, which has frequently been broken thereby. Moreover, theconstruction mustbe such `that the yielding element shall always recoveritself when the expansion ceases and contraction sets in. If the convexbottom of the expansion-chamber snaps into the oppo- IOO IIO

elasticity would be destroyed, besides the site form-that is to say, ifit is pushed downward until itsliquid-containing face is con-V cave-itis possible that it may remain in that form, especially if aconsiderable force is required in order to press the inclosing rimoutward far enough to permit the bottom to spring back to its normalposition.

My invention makes ample provision for all these requirements. Theelastic rim surrounding the bottom and connected integrally with theouter surrounding flange ork rim will readily spring' outward andinward, and as the bottom is pressed by the' oil the elastic yield isample to accommodate even' greater volumes of fluid than that driveninto the expansion-chamber by the maximum expansion met with. The normaltendency of this elastic rim to return to its place also` assists theelastic bottom in resuming its. normal form, and I am thus able to uselighter metal for the bottom of said expansion-chamber, as part of theelasticity is locatedv in the rim 25. If this rim were rigid andunyielding, the pressure upon the convex bottom of the expansion-chamberwould when excessive spring the convex bottom outward, andas there wouldbe no yield in the rim the bottom would necessarily buckle, and part ofits danger of rupturi ng the metal. It would be very likely, also, to soweaken the tendency of the bottom to resume its position that it wouldafter a few expansions remain permanently in the expanded positionunless external force were used to restore it. My construction alsogreatly facilitates the repairing of the compass, as theexpansion-chamber may be removed by simply detaching the ballast weightand applying pressure by means of the screw-plug closing thefillingopening, by which the flange 24 will be driven out of the iiangeon the bottom of the compass-bowl.

lVhat I claim isl. In a mariners compass, a compass-card consisting of acard-annulus having bridgepieces on opposite sides of its center, theirends upon the surface of the card, and magnetized needles passingthrough openings in angular strips forming part of said bridgepieces andextending at suitable intervals over and upon the surface of the card,the

terminals of said needles being substantially coincident with theperiphery of the card, substantially as described.

2. In a liquid-compass, the combination, with a bowl, of anexpansion-chamber with which the bowl communicates, the expansionchamberhaving a bottom which is convex upon its inner or liquid-containingsurface, said bottom having an integral surrounding rim `which is bentover outwardlyupon itself to form an outer rim or fiange, by which thebottom of the chamber is attached beneath the compass-bowl, and-toprovide an elastic ring between the outer rim or flange and the convexbottom of'the expansion-chamber, which will yield outwardly whenpressure is applied to the convex face of the bottom of saidexpansion-chamber, substantially as described.

3. In a mariners compass, the combination, with a card having acard-annulus, of a series of magnetized needles arranged in parnallelismand supported in bridge-pieces extending on opposite Vsides of theequatorial center, a ring air-'chamber mountedV on said bridge-pieces,and a pivot-bearing having a detachable agate seat for thepin,substantially as described.

4. In a mariners compass, a'compass-card composed of acard-annulus,magnetized needles arranged in bridge-pieces lying parallel with theequatorial line and having angular strips provided with openings toreceive the needles, the latter having their ends coincident with theperiphery of the card, a compass-bowl having a central pivotal bearingentering a seat attachably and detachably mounted on the needles of thecard, and a body of juniper or other oil contained in the bowl,substantially as described. 5. In a mariners compass, a closedcompass-bowl having an expansion-chamber, the bottom of which is convexon its upper face and provided with an elastic circumferential rimuniting said bottom to an outer rim or fiange, by which said bottom maybe secured in position, substantially as described.

6. In a mariners compass, the combination, with a compass-bowl, of acommunicating expansion-chamber, the bottom of which is slightly convexon its lliquid -containing face and provided Witha circumferential rimor iiange, between which and the bottom of said chamber is an elasticrim rising above the floor and formed by bending the metal upon itselfto form the'flange, the circumferential rim or flange being rigidlyattached to a circular flange depending from the compassbowl,substantially as described.

7. In a mariners compass, the combination, with a card, of a series ofmagnetized needles arranged in parallelism and supported inbridge-pieces extending on opposite sides of the equatorial center, anattachable and detachable ring air-chamber mounted on saidbridge-pieces, and a pivot-bearing having a detachable agate seat,substantially as described.

In testimony whereof I have hereunto set my hand and affixed my seal inpresence'of two subscribing witnesses. i

ROBERT. oLIvER. [n s] Vitnesses: Y GEO. W. HUNT, 4 DE-HART BERGEN, Jr.

IOC

